Videos: The HAC Discovery Channel

In this section you will find links to YouTube videos/animations that the team have produced during the project. There are also some links to some incredible videos produced by others.

“MicroHAC demonstration”. This video ( explains how a mine-scale HAC might be configured for deployment in a single mine raise (shaft). It was filmed in May 2018 at the Dynamic Earth HAC in Sudbury. Although it is small, this HAC works by exactly the same principles as its big brother, but has the advantage what we can easily carry it around to provide demonstrations to interested people. Also visitors to Dynamic Earth who chose to tour the HAC can fill, operate and run experiments with this scaled down system. For teachers and their pupils, we have created a activity leaflet.

MicroHAC demonstration model


“Detrainment Bubbles at Baby HAC”

Bubbles in Baby HAC

One of the nice features of an iphone is that it has a “slo-mo” option for taking videos. Valeria Pavese shot this video ( while she was running carbon capture experiments on the BabyHAC at Dynamic Earth. One of the special conditions of this particular experimental run is that the water flow rate through the system was low. Under these conditions we often see examples of bubble detrainment in the downcomer flow, and this is illustrated in this particular clip.

What we think is going on is as follows. As the gas is compressed, its volume falls, and the volume ‘defect’ is ‘replaced’ with water volume. The water, being an incompressible fluid, in occupying this new volume reduces its average velocity across the downcomer pipe section. The reduction in velocity, reduces drag on the individual bubbles and so the relative velocity between water and bubble falls too. The bubbles eventually ‘bunch up’ so densely that they are forced to coalesce into a ‘slug’, and this also creates a relatively ‘bubble free’ zone below the slug. The water free falls, and thus accelerates, through the slug, and impacts on the water surface at the base of the slug. This creates a time-averaged impact pressure that we have sensed below the slug. The higher velocity of the water at the point of impact, also seems to be sufficient to re-entrain the air, and create new gas bubbles, so that the HAC compression process resumes downward. When detrainment occurs, it essentially represents a back flow of gas, up (!) the downcomer. In the video clip, we track the slug up towards the air-water mixing head. This behaviour is exacerbated when the volumetric flow rate of water into the downcomer is set low, so that superficial water velocity is low at the start of the compression process.

“Air entrainment in the Taylor Head”

In this video, filmed by Dean Millar and David Vitone, we show the onset of air entrainment using the Taylor Head at Dynamic Earth. The experimental set up is that we have blocked off the discharge nozzle of one of the two pumps at its flange in the forebay tank, and are running on just one pump. As water is lifted into the forebay tank, the tank water level rises and eventually spills over into the convergent section of the Taylor Head. At this point, water flows across the horizon containing the hydroplanes, and creates a low pressure zone due to the Bernoulli effect. The upper part of the Taylor Head is, in essence, a manifold that guides air from the snorkel pipe to 188 air inlet tubes. The mouths of these tubes are positioned at the low pressure zones between the hydroplanes, such that the water low pressure inducts air through the manifold. At around 1:00 minute into the video, we look into the forebay tank toward the discharge nozzle of the single pump that is running. A hydraulic jump can clearly be seen. We have plans to add a divergent section to this nozzle to recover the kinetic energy of the pump discharge, but are not too concerned about this because the hydraulic jump clearly helps to “pre-aerate” the water too.


“Full speed forebay tank action”. This video shows the water motion in the forebay tank with both of the water circulation pumps in motion, at the highest speed we can set on the variable frequency drives. Mesmerizing!

Air entrainment at full speed


“Around the HAC in 53 seconds” This video shot close to dusk, was from a drone around the Dynamic Earth Hydraulic Air Compressor. The drone pilot was Peter Pakalnis, visiting Sudbury from Ottawa on Saturday 17th June, 2017. Thank you for sharing this video with us Peter; it’s a perspective on the facility that we have not seen before!

As far as I am aware, this is a video of the last time the Ragged Chutes plant was operated – June 6th, 1988. This was after a prolonged shut down. The video features footage of the air water mixing heads in operation – modified by the addition of some modern plastic air pipes that passed down inside the historical air pipes. There is also wonderfully clear imagery of the blow-off in operation – near continuously. If anyone needs to be convinced why pneumatic power production using hydraulic air compressors is a principle that needs to be revived, then this is it. Enjoy!

Produced by William Sutton of Cobalt, ON. Posted Aug 26, 2016.

I met Dan Larocque at the Bunker Museum in Cobalt in 2013, during my earlier investigations into hydraulic air compressors. Dan has produced a video taken with a drone, flying over the site in February 2017. This is a fantastic piece Dan! A wholehearted thank you for allowing us to share this – from the whole team!



Disrupt Mining!

Disrupt Mining Video

Electrale Innovation entered the #disruptmining competition. In this video Dean Millar explains why we entered and what the judges could expect in the competition entry:

ABCs of HACs

“The ABCs of HACs” is an animated narrative that explains some of the history of HACs, how they work, and how HACs are being improved through the efforts of the HAC Demonstrator Project Team (the ‘HAC Pack’).

‘Baby HAC’ in operation: This short clip shows Baby HAC running at the HAC Lab in the Glencore Innovation Centre at Cambrian College, Sudbury.



Time-lapse erection of Baby HAC

Erection of the ‘Baby HAC’. This is a time-lapse video taken over a few days, mainly showing Alex Hutchison erecting the pilot scale prototype:

Voyage to the center of the HAC. This video shows footage of a sewer camera traverse down the length of the riser space of the HAC at the Peterborough Lift Lock. Most of the action is at the start of the video. The camera became obstructed further down. Thanks to our friends at Parks Canada for permitting us to do this and helping us get access to the compressor. The compressed air produced by the system used to be used to open and close the doors of the two huge tanks that permitted canal boats to gracefully descend the ~20 metres from the upper reaches to the lower reaches of the Trent Severn Canal.


You may also be interested in the integrating theme of the research and innovation program of the Energy, Renewables and Carbon Management group at MIRARCO Mining Innovation. In this 20 minute video, Dean Millar explains the so-called The ‘40% Mine’ concept .